1. Field of the Invention
The invention relates to a receiving system for a digital broadcasting for receiving a signal in which, for example, video data and audio data are broadcasted by a transport stream of an MPEG (Moving Picture Experts Group) 2 system and transmitting the transport stream to digital signal processing equipment through an interface of IEEE (Institute of Electrical Electronic Engineers) 1394. The invention also relates to a data transmitting method in such a digital broadcasting receiving system and a receiving apparatus for a digital broadcasting which is used for such a system.
2. Description of the Related Art
In recent years, IEEE1394 has been started to spread as an interface to transfer video data and audio data between digital video equipment and digital audio equipment at a high speed. In IEEE1394, an isochronous transfer mode and an asynchronous transfer mode are supported. The isochronous transfer mode is suitable to transfer a time-sequential data stream such as video data or audio data at a high speed. The asynchronous transfer mode is suitable to transfer, for example, various commands or the like.
In recent years, a digital satellite broadcasting has been started to spread. In the digital satellite broadcasting, a digital video signal and an audio signal are compressed by the MPEG2 system, multiplexed by a packet stream, and transmitted. When a digital satellite broadcasting is received, an IRD (Integrated Receiver Decoder) is connected to a television receiver. A signal of a desired program is selected by the IRD and a video signal and an audio signal are decoded. An output of the IRD is supplied to the TV receiver.
A method of providing the interface of IEEE1394 for the IRD to receive such a digital satellite broadcasting has been proposed. When the interface of IEEE1394 is provided for the IRD, the IRD is connected to a digital video recording and reproducing apparatus or an MD recording and reproducing apparatus through the interface of IEEE1394 and a receiving system for the digital satellite broadcasting can be constructed.
In IEEE1394, when data is transferred, an ID number of a node is allocated and a partner is designated by the ID number of the node between equipment connected to a bus of IEEE1394. The number of nodes of one bus is equal to 64 on the IEEE1394 standard. The numbers “0” to “63” are allocated as node ID numbers. The last node number “63” among them is used for broadcasting. In such a system, for example, in case of recording data received by the IRD, equipment on the partner side to record is designated and data is transferred from the IRD to the equipment on the partner side. Therefore, the channel for broadcasting having the node No. “63” is not used generally.
In such a system, however, there is a possibility such that new equipment will be added to the system in future. For example, now assuming that a dedicated decoder is connected to a digital satellite broadcasting and an HDTV picture plane is decoded, there is a possibility such that the decoder is added to the system. In the case where such new equipment is added to the system, since equipment cannot be specified, it is difficult to allocate the node number and transmit data.
To prepare for a situation such that such equipment which cannot be specified is connected, therefore, a method of enabling a broadcasting channel to be used is considered. In the broadcasting channel, since it is connected to the bus and data is sent to all equipment, the data can be transmitted without specifying equipment.
In case of enabling the data to be transmitted by using the broadcasting channel as mentioned above, it is necessary to also enable the data to be transmitted to undefined equipment. For example, among digital video tape recording/reproducing apparatuses, there is equipment which can receive and record a transport stream of MPEG as it is. It is necessary to transfer data to such equipment by the transport stream of MPEG. However, in digital audio equipment such as an MD recording/reproducing apparatus, even if the MPEG transport stream is received, it cannot be decoded. It is, therefore, necessary to transfer PCM audio data to such equipment.
As mentioned above, even if the broadcasting channel can be used, if the kind of data which is used in the broadcasting channel cannot be set, it is impossible to cope with a case where new undefined equipment is connected.